摘要:

The synthesis of cyclohexyl 2-acetamido-2-deoxy-3-O-{2-O-[2-(guanosine 5′-O-phosphate)ethyl]-α-L-fucopyranosyl}-β-D-glucopyranoside (1), a potential inhibitor of α(1→3)fucosyltransferases, is described. Target compound1was assembledviafucosylation of cyclohexyl 2-acetamido-2-deoxy-4,6-O-isopropylidene-β-D-glucopyranoside (6) with ethyl 2-O-[2-(benzoylhydroxy)ethyl]-3,4-O-isopropylidene-1-thio-β-L-fucopyranoside (5) followed by debenzoylation, subsequent condensation of the resulting compound with 3′,4′ -di-O-benzoyl-5′ -O-(2-cyanoethyl-N,N-diisopropylphosphoramidite)-2-N-diphenylacetylguanosine (10) and deprotection.

ISSN:0732-8303    

DOI:10.1080/07328309508005410

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Efficient conversion of a range of different phenyl thioglycosides into their hemiacetals has been achieved by treatment withN-bromosuccinimide in aqueous acetone. The method is mild and general since it does not interfere with the presence of other protecting groups like acetate, benzyl, benzylidene acetal,tert-butyldiphenylsilyl groups, and theO-glycosidic bond (e.g. di-, tetra-, and pentasaccharide thioglycosides).

ISSN:0732-8303    

DOI:10.1080/07328309508005411

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Cycloaddition of sodium glyoxylate, in water, onto penta-2,4-dienol provided 2-deoxyheptulosonic acid derivatives. Activation of the anomeric carbon was achieved through NBS mediated C-2-C-3 dibromination.

ISSN:0732-8303    

DOI:10.1080/07328309508005412

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The stereochemical outcome of the hetero Diels Alder reaction of an erythrose based diene with sodium glyoxylate was rationalized by preparing the same compounds via decarboxylation of 2-carbethoxy-2-deoxy-2-ulosonic esters, obtained by cycloaddition with diethyl ketomalonate. Further chemical transformations of cycloadducts allowed us to prepare a series of new 2-nonulosonic acid derivatives.

ISSN:0732-8303    

DOI:10.1080/07328309508005413

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A diastereomeric mixture of nitriles1a,bwas prepared by a Strecker synthesis from D-glyceraldehyde acetonide and benzylamine. The reported selective hydrolysis of the acetonide group of1acould not be accomplished. Nitrile diastereomers1a,bwere carried forward as a mixture to amines3a,bwhere the diastereomers were readily separable. The hydrochloride of3awas transformed via sequential debenzylation,N-acetylation, reduction, and exhaustive acetylation to the 2-amino-2-deoxy-D-threose derivatives5and6. The corresponding 2-amino-2-deoxy-D-erythrose derivatives10aand11were prepared similarly from amine3b.

ISSN:0732-8303    

DOI:10.1080/07328309508005414

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The tributyltin hydride + AIBN mediated free radical cyclization of oxime ethers tethered dithioacetals6and12, obtained from D-ribose or D-glucose, respectively, is reported. The desired carbocycles7, 8and14have been obtained in good yield and moderate diastereoselectivity. These products are new mannostatin A analogues.

ISSN:0732-8303    

DOI:10.1080/07328309508005415

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Reaction of the 4-C-lithiomethyl intermediates, obtained from 4-deoxy-4-C-iodomethylglucopyranosides5a,b, with open-chain glucose derivative8afforded 4-deoxy-4-C-heptitylglucopyranosides9a,b. Mesylation of the newly generated hydroxy group and then desilylation gave11a,bwhich were subjected to ring closure under basic conditions. Surprisingly, noC-bridged cellobiosides12a,b(or, alternatively the corresponding maltosides) were obtained as major products; with loss of one benzyl alcohol residue the furanosides13a,bwere preferentially formed. Their generation and structural assignment is discussed.

ISSN:0732-8303    

DOI:10.1080/07328309508005416

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

A general synthetic approach to enantiomerically pure 4-substituted 2,4-dideoxypentopyranosides has been developed which provides access to the 4-alkylamino-2,4-dideoxy-L-threo-pentopyranose components of the calicheamicins and esperamicins.

ISSN:0732-8303    

DOI:10.1080/07328309508005417

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

The synthesis of a new β-cyclodextrin derivative containing a dithiocarbamate group (3) by condensation of mono-2-methylamino-2-deoxy-β-CD (2) with CS2in the presence of NEt3is reported. SOD-mimetic activity was found for the Mn(II) and Cu(II) complexes of2and3(IC50= 0.76-7.4 μ). To study the influence of the cyclodextrin residue on the catalytic activity of these complexes, a comparison was made with diethylamine and diethyldithiocarbamate complexes. Complexes of2and3resulted in 1.3 to 11 fold higher activities. An explanation for this observation, in terms of a possible cooperation of the cyclodextrin residue with the catalytic center of the complex, is given.

ISSN:0732-8303    

DOI:10.1080/07328309508005418

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor

摘要:

Analogues of nucleosides in which the nucleobase is fixed onto the C-4 of the sugar moiety are generally prepared either from 4,5-unsaturated sugar derivatives orviaa formaldehyde condensation.1We tested the furanosyl bromide reactivity of12towards a series of nucleophiles, mostly azides or cyanides, without success. Conversely, the nucleosidation of1using 5-methyl-2,4-bis(trimethyl-silyloxy)pyrimidine in the presence of stannic chloride took place at the second anomeric position (C-4) and led to the isolation in acceptable yield (47%) of a unique anomer2(Scheme 1).

ISSN:0732-8303    

DOI:10.1080/07328309508005419

出版商:Taylor & Francis Group    

年代:1995

数据来源: Taylor